5
$\begingroup$

I know that it is kerosene based, but what exactly goes into it? Proportions of the various components would be helpful.

$\endgroup$
3
  • $\begingroup$ Its made with pure kerosene and anti freeze. (en.wikipedia.org/wiki/Aviation_fuel) This is where I got the information. $\endgroup$ – Ethan Dec 8 '15 at 23:38
  • $\begingroup$ @fooot -- I'm not thinking of this as a dupe b/c it focuses in specifically on jet fuel, vs the "what fuels are out there?" of the linked Q -- they're certainly related, though. $\endgroup$ – UnrecognizedFallingObject Dec 9 '15 at 3:21
  • $\begingroup$ @UnrecognizedFallingObject but answers to the linked question still explain what the components are, as well as other fuels. $\endgroup$ – fooot Dec 9 '15 at 15:03
8
$\begingroup$

Sadly, that information's pretty much impossible to give a general answer for, as it changes from batch to batch:

  • Refineries blend crude "to taste" as well as pricetag, so to speak, and the crude blend used as the refinery feedstock may change from batch to batch.
  • Process conditions in catalytic crackers and reformers can change depending on the point in the batch you're at, the incoming feedstock, and even the history of prior batches (say the last thing that ran through the cat cracker degraded the catalyst slightly...)
  • Jet fuels as-delivered may be a blend of multiple refinery batches and even the output of multiple refiners
  • Pipeline batching can also lead to subtle changes in fuel composition as it is transported -- pipeline operators try to "cut off" as much of the transmix as they can, but 100% isn't easy without wasting tons of fuel as transmix. (Some pipeline operators will stick a "dumb pig" between high spec products, such as jet fuel, and their neighbors in the pipeline, but this is by no means universal.)

That said, you can make some determinations based off of a representative SDS for Jet-A, courtesy of ConocoPhillips:

  • The fuel consists of medium-weight hydrocarbons, from C9 to C16
  • The only specified aromatic component is napthalene, with a maximum concentration of 3%
  • No additives (anti-static, FSII, anti-oxidation, biocidal) are specified -- these are generally variable from batch-to-batch, depending on the specific purchaser (a large airport might get to spec these directly with the refiner, while the small GA 'dromes are at the mercy of whoever pulls up in the fuel truck)
$\endgroup$
3
  • $\begingroup$ I'd always been told that all aviation fuel was strictly controlled, to be essentially the same no matter where it's bought. These differences in batches & blends must have practically zero effect on engine performance, right? $\endgroup$ – Xen2050 Dec 9 '15 at 5:15
  • $\begingroup$ @Xen2050 -- Yes -- the ASTM/... specs for Jet-A control all the important properties well enough that jet fuel is a commodity product -- any batch of Jet-A that meets spec will function "as advertised" in anything type certificated to run on Jet-A. (If you really wanted to know the exact makeup of a batch of jet fuel, you'd probably need to ask a friendly chemist to assay the batch, but that's expensive, tedious, and generally unnecessary as the Jet-A spec is largely performance based anyhow.) $\endgroup$ – UnrecognizedFallingObject Dec 9 '15 at 5:20
  • 1
    $\begingroup$ @Xen2050, the differences do have practically zero effect on engine performance, but not because they are small. It's because the engines will run on about anything as long as it has sufficient specific heating value, ignition temperature in the right range and is slippery enough to keep the fuel pumps happy. $\endgroup$ – Jan Hudec Mar 30 '17 at 19:32

Not the answer you're looking for? Browse other questions tagged or ask your own question.